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OLD FIELD SUCCESSIONAL DYNAMICS FOLLOWING CESSATION OF CHRONIC DISTURBANCE
Citation:
Tunnell, S. J., D. M. Engle, AND E E. Jorgensen*. OLD FIELD SUCCESSIONAL DYNAMICS FOLLOWING CESSATION OF CHRONIC DISTURBANCE. JOURNAL OF VEGETATION SCIENCE 15(3):431-436, (2004).
Description:
In grasslands dominated by warm-season grasses, community composition and successional patterns can be altered by disturbance and exotic species invasions. Our objective was to describe vegetation dynamics following cessation of a chronic disturbance (heavy grazing by cattle) in an old-field grassland subject to invasion by Festuca arundinacea, an introduced grass. Specifically, we evaluated changes in plant community composition and investigated the relationships between species richness and litter accumulation and between species richness and abundance of Festuca. Vegetation data consisted of canopy cover by species, species richness, and litter mass collected on 16, 40 x 40-m plots within an old-field site in southeastern Oklahoma, USA. The predictable successional patterns observed in similar old fields following cessation of grazing were altered by an increase in abundance of Festuca over the three-year study period. Moreover, the expected negative correlation between litter accumulation and species richness demonstrated in similar North American mesic grasslands was not observed in this old field. Rather, Festuca and species richness were negatively correlated, but on plots in which Festuca increased, species richness did not decrease. Instead, Festuca increased most on species-poor plots, and Festuca abundance remained low on species-rich plots. We conclude that the influence of Festuca on plant community composition was tied primarily to species richness.